Loads at a customer location may be curtailed or interrupted during power system events for several reasons. Depending on the driver, the load reduction may be initiated by the utility or by the customer. For the customer, load reduction is generally an attempt to decrease energy consumption during certain periods of time to reduce costs. Predetermined loads such as HVAC, hot water heaters, pool pumps, or other high consumption devices can be selected for energy interruption to reduce the overall consumption when higher energy prices are in effect.
For the utility, load shedding at a customer site may be accomplished because of an abnormal condition on the power network. Abnormal conditions include events such as loss of transmission capability due to a line outage, loss of generation, loss of inter-tie to adjacent power networks, unusually high peak demand or similar type events. In this case the utility may take different steps to decrease consumption via load shedding. Load shedding can be initiated at the substation level using frequency-based relays. Many customers may contractually elect to have non-critical loads interrupted at customer premises for a reduction in overall energy costs. In order for this to be effective, the utility traditionally interrupts certain loads for a few minutes to maybe hours in order to reduce the overall load on a transmission network.
One drawback of such systems is that they require additional equipment at a customer premises and additional systems to manage the equipment. With the rapid growth in fixed network automated reading systems, it would advantageous if such systems could be used to manage load control systems to reduce the amount of equipment and systems necessary to implement load control and shedding. The present invention provides such a system.